The long term goal of this research area is to investigate the perception, decision and action processes involved in collision and injury avoidance with respect to both expected (but unnatural) and unexpected robot movements. Today's industrial robots perform their tasks with high speed of movements, unpredictable motion patterns, and variable working envelopes or danger zones. Robot operators have been seriously injured and killed partly due to misperception of these nontraditional characteristics of robotic systems. This research addresses the perceptual hazards associated with robotic systems and offers experimental data to design and maintain safer robotic work stations. Experiment #1 investigates operator perception of robot arm speed and determines the maximum speed that robot operators judge to be "safe". As an industrial robot performs a simulated 10-minute pick-and-place palletizing task, the subjects will be instructed to adjust the robot's maximum arm speed (up or down) until a final "safe" speed is determined. To protect the subjects, all the experimental sessions are conducted with subjects positioned outside the robot's working envelope using empty robot grippers. Experiment #2 investigates the minimum amount of time for robot arm inactivity (idle time) to be perceived as either programmed stop or system problem such as malfunction. Random stops of different durations are introduced into a 10- minute palletizing task. The subjects are instructed to indicate which stops are perceived to be preprogrammed and which ones are malfunction needing operator's intervention. Experiment #3 determines the robot work envelope which is perceived to be hazardous for robot operators. After demonstration of a 10- minute palletizing task, the main power source of the robot will be shut down, and the subjects will be instructed to approach the robot's work area to the closest point they consider to be safe from all directions. These points will be marked for two different robot types and speeds. Analysis of variance will be used to determine the effect of speed on dependent measures of idle time and average robot danger zone area. These data are expected to be used in NIOSH recommendations and ANSI standards for safe design of robot workstations.